In the course of processing, handling, storage, or use, lube oil basestocks, can pick up a not-insignificant quantity of water. For the purposes of this specification and the appended claims, lube oil base stocks are to be understood as being lube oil stocks which have been solvent extracted and/or dewaxed and/or hydrotreated.
The presence of water introduces a performance concern in the use of the oil. A major performance requirement of circulating oil (which is the usual mode of performance of a lube oil) is that the oil possess good demulsibility. By demulsibility is meant the ability of the base oil to separate from water after the water and oil have been intimately contacted and agitated. Water contamination and entrainment (evidenced by poor demulsibility) results in an impaired oil flow and impaired lubricity. The addition of demulsifiers does not always improve demulsibility performance. Furthermore, the addition of demulsifier additives increases costs.